Effect of UVB Irradiation on Cu2+-Binding Organic Ligands and Cu2+ Speciation in Alpine Lake Waters of New Zealand

2005 ◽  
Vol 2 (1) ◽  
pp. 56 ◽  
Author(s):  
Sylvia Sander ◽  
Jonathan P. Kim ◽  
Barry Anderson ◽  
Keith A. Hunter
Keyword(s):  
New Zealand ◽  
Surface Waters ◽  
Natural Waters ◽  
Austral Summer ◽  
Organic Ligands ◽  
Conditional Stability ◽  
Uvb Radiation ◽  
Dissolved Metals ◽  
Conditional Stability Constant ◽  
Uvb Irradiation

Environmental Context. The bioavailability of dissolved metals in natural waters is directly affected by metal-sequestering agents. These agents include soil-derived matter and compounds released by microorganisms, since copper can support or inhibit aquatic microorganisms depending on concentration. During summer the levels of copper increase in surface waters, an effect intuitively attributable to increased ultraviolet light degrading the sequestering agents more effectively, leading to a concurrent release of the metal. This paper shows that the amount of degradation attributable to light is too low to explain the metal release and that a biological influence may instead be responsible. Abstract. The influence of UVB irradiation on the Cu2+ binding by natural organic ligands in six alpine lakes on the South Island, New Zealand, has been investigated using competitive ligand equilibration with salicylaldoxime and detection by cathodic stripping voltammetry (CLE-CSV). During austral summer 2002–2003 the total dissolved Cu ([Cu]T), the concentration of strong Cu2+-binding ligands ([L]T), and their conditional stability constant K´´ were determined in surface samples of all six lakes. All lakes exhibited appreciable concentrations of a strong Cu2+ binding ligand with similar K´´ values and concentrations always exceeding [CuT], thus dominating Cu2+ speciation. Four lakes (Hayes, Manapouri, Wanaka, Te Anau) showed no appreciable trend in [LT] throughout the summer, whereas in Lakes Wakatipu and Hawea [LT] increased steadily throughout this period. Laboratory UVB irradiation of lake water samples using a 400 W mercury lamp with a Pyrex glass filter (λ > 280 nm) showed that Cu2+-binding ligands are destroyed by UVB radiation, causing [L]T to decrease with a rate of –0.588 nmol L–1 h–1 (r2 0.88). From this we calculate that the in situ ligand destruction rate by UVB in summer for surface waters of these lakes is too small to significantly affect [LT], and conclude that variations in ligand concentrations must result from seasonally variable biological factors.

Zinc speciation in Lakes Manapouri and Hayes, New Zealand

2001 ◽  
Vol 52 (2) ◽  
pp. 217 ◽  
Author(s):  
Michael J. Ellwood ◽  
Michael J. Ellwood ◽  
Keith A. Hunter ◽  
Keith A. Hunter ◽  
Jonathan P. Kim ◽  
...  
Keyword(s):  
New Zealand ◽  
Stability Constants ◽  
Surface Waters ◽  
Zinc Concentration ◽  
Organic Ligands ◽  
Ligand Concentration ◽  
Conditional Stability ◽  
Zinc Speciation ◽  
Zinc Concentrations ◽  
Conditional Stability Constants

A study of zinc complexation in Lakes Manapouri and Hayes revealed that zinc speciation in both lakes is dominated by its complexation to natural organic ligands. In Lake Manapouri, dissolved zinc concentrations increased from 0.9 nM in surface waters to ~1.4 nM at depth. Ligand concentrations for this lake were relatively uniform with depth, with values ranging between 2.9 and 4.2 nM. A similar ligand concentration was measured for Lake Hayes, which had a surface zinc concentration of 0.46 nM. Conditional stability constants (log K) for the complexation of zinc to these ligands were high,with values ranging between 10.0 and 11.1. Calculated free Zn 2+ concentrations for both lakes were in the low picomolar range (5—48 pM). Such low free Zn 2+ levels may limit the growth of some phytoplankton in both lakes.

F-specific bacteriophage as an indicator of human viruses in natural waters and sewage effluents in Northern New Zealand

1995 ◽  
Vol 31 (5-6) ◽  
pp. 231-234 ◽  
Author(s):  
Gillian D. Lewis
Keyword(s):  
New Zealand ◽  
Comparative Study ◽  
Marine Environment ◽  
Natural Waters ◽  
Sewage Effluents ◽  
Pathogenic Viruses ◽  
Human Viruses ◽  
Specific Bacteriophage ◽  
Beach Water

To assess the F-specific bacteriophage as an indicator of pathogenic viruses, a comparative study has been made of the occurrence of F-phage and human enteroviruses in sewage wastes and the marine environment. Although F-phage seemed in several respects to match pathogen behaviour, its low abundance in bathing beach water, uncertainty as to its source and other detection irregularities make its use as an indicator problematical.

Biodegradation studies as an important way to estimate the environmental fate of chemicals

1999 ◽  
Vol 39 (10-11) ◽  
pp. 375-382
Author(s):  
Andreja Žgajnar Gotvajn ◽  
Jana Zagorc-Končan
Keyword(s):  
Surface Waters ◽  
Natural Waters ◽  
Environmental Fate ◽  
Standard Test ◽  
Screening Tests ◽  
Natural Systems ◽  
Additional Information ◽  
Assessment Tests ◽  
Ready Biodegradability ◽  
Biodegradability Assessment

Biodegradation is confirmed as an important mechanism of organic chemicals removal in natural systems. Estimation of biodegradability of chemicals which reach the aquatic environment in significant or even negligible quantities is necessary in assessing the entire hazard associated with their use. The aim of our study was to compare the standardized ready biodegradability assessment test (closed bottle test) and its modifications, employing the basic agreements on test principles of simulation of biodegradation in surface waters, yet no official standard method has been adopted. The standard test was modified using various natural river waters and a variety of nutrient conditions and microbial species trying to simulate the natural environment in the simplified way. Tests were performed with two compounds with different ability to degrade. Experiments indicate that predictability of biodegradation obtained by ready biodegradability assessment tests for surface waters in many cases is not reliable, because of different conditions, which may prevail in surface waters over time and affect biodegradation. However, the use of natural waters in screening tests assures additional information on fate of chemicals in rivers and lakes.

scholarly journals Spectrophotometric determination of dothiepin hydrochloride in pharmaceuticals through ion-pair complexation reaction

2012 ◽  
Vol 18 (2) ◽  
pp. 339-347 ◽  
Author(s):  
Sameer Abdulrahman ◽  
Kanakapura Basavaiah
Keyword(s):  
Ion Pair ◽  
Pure Form ◽  
Bromocresol Green ◽  
Bromophenol Blue ◽  
Complexation Reaction ◽  
Conditional Stability ◽  
Conditional Stability Constant ◽  
Accuracy And Precision ◽  
Significant Difference

Two simple, sensitive and extraction-free spectrophotometric methods are described for the determination of dothiepin hydrochloride (DOTH) both in pure form and in pharmaceutical tablets. The methods are based on ion-pair complex formation between dothiepin base (DOT) and two acidic dyes, namely, bromophenol blue (BPB) or bromocresol green (BCG) with absorption maximum at 425 nm for BPB method or 430 nm for BCG method. Beer?s law is obeyed over the concentration ranges of 1.0-15.0 and 1.0-17.5 ?g mL-1 DOT for BPB and BCG methods, respectively. The molar absorptivity values and Sandell?s sensitivity values are reported for both methods. The limits of detection (LOD) and quantification (LOQ) were calculated to be 0.18 and 0.53 ?g mL-1 for BPB method, and 0.17 and 0.50 ?g mL-1 for BCG method, respectively. The stoichiometry of the complex in either case was found to be 1: 1 and the conditional stability constant (KF) of the complexes has also been calculated. The proposed methods were applied successfully to the determination of DOTH in pure form and in its tablet form with good accuracy and precision. Statistical comparison of the results was performed using Student's t-test and variance ratio F-test at 95% confidence level and there was no significant difference between the official and proposed methods with regard to accuracy and precision. Further, the validity of the proposed methods was confirmed by recovery studies via standard addition technique.

scholarly journals Spectrophotometric determination of nicradipine and isradipine in pharmaceutical formulations

2009 ◽  
Vol 15 (2) ◽  
pp. 69-76 ◽  
Author(s):  
S.M. Al-Ghannam ◽  
A.M. Al-Olyan
Keyword(s):  
Standard Deviation ◽  
Detection Limit ◽  
Reaction Pathway ◽  
Pharmaceutical Preparations ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Zinc Powder ◽  
Conditional Stability ◽  
Conditional Stability Constant

A sensitive spectrophotometric method was developed for the determination of some 1,4-dihydropyridine compounds namely, nicardipine and isradipine either in pure form or in pharmaceutical preparations. The method is based on the reduction of nicardipine and isradipine with zinc powder and calcium chloride followed by further reduction with sodium pentacyanoaminoferrate (II) to give violet and red products having the absorbance maximum at 546 and 539 nm with nicardipine and isradipine, respectively. Beer's law was obeyed over the concentration range 8.0-180 ?g/ml with the detection limit of 1.67 ?g/ml for nicardipine and 8.0-110 ?g/ml with the detection limit of 1.748 ?g/ml for isradipine. The analytical parameters and their effects on the reported methods were investigated. The molar absorptivity, quantization limit, standard deviation of intercept (Sa), standard deviation of slope (Sb) and standard deviation of the residuals (Sy/x) were calculated. The composition of the result compounds were found 1:1 for nicardipine and 1:2 for isradipine by Job's method and the conditional stability constant (Kf) and the free energy changes (?G) were calculated for compounds formed. The proposed method was applied successfully for the determination of nicardipine and isradipine in their dosage forms. The results obtained were in good agreement with those obtained using the reference or official methods. A proposal of the reaction pathway was presented.

scholarly journals Spatial & Temporal Patterns of Microplastic Pollution in Wellington, New Zealand, and the Southern Ocean

2021 ◽  
Author(s):  
◽  
Caitlyn Shannon
Keyword(s):  
New Zealand ◽  
Southern Ocean ◽  
Spatial Variation ◽  
Marine Environment ◽  
Surface Waters ◽  
Environmental Drivers ◽  
Plastic Pollution ◽  
Temporal And Spatial Variation ◽  
Beach Sediments ◽  
Temporal And Spatial

<p>The global marine environment is currently facing unprecedented anthropomorphic change and stress. One such stressor is plastic pollution, which has continually increased in magnitude since mass production began in the 1940’s. An increase in plastic debris throughout the oceans not only results in an infiltration of the pollutants throughout the entirety of the marine environment, but also increases the risk that it impacts the physiological, structural, and behavioural traits of various organisms – including humans. These negative interactions are particularly likely with microplastic particles (< 5 mm), as they can enter and be transferred throughout the food web with ease. However, research in the field of microplastic pollution is extremely one-sided, with most present studies focusing on the Northern Hemisphere. Additionally, comparatively little has been investigated regarding temporal and spatial patterns of microplastic occurrence. The aim of this research was to 1) examine the abundance and distribution of synthetic particles in sub-surface waters of the Southern Ocean, across broad temporal and spatial scales and 2) examine finer-scale spatial and temporal patterns of microplastic load within the urbanised Wellington Harbour, New Zealand, using a combination of environmental and biological indicators.  To assess the broad-scales of temporal and spatial variation in the Southern Ocean, annual Continuous Plankton Recorder (CPR) tows were undertaken between New Zealand waters and the Ross Sea, Antarctica, over a span of 9 years (the austral summers of 2009/10 – 2017/18) and a range of 5 oceanographic zones and two frontal systems, totalling a distance of approximately 22,000 km. Overall, patterns were inconsistent, with no constant increase or decrease in load throughout the years, while spatial variation was minimal and not associated with particular oceanographic fronts or proximity to an urban area. Despite no consistent spatial variation, temporal differences did occur between years. Again, there were no identifiably consistent trends across years (i.e. a gradual increase), but there was a substantial peak in 2009/10 and a trough in 2012/13. Such changes are likely due to large-scale variations in ocean circulation systems, along with environmental drivers such as El Niño and La Niña events.  To investigate the microplastic load in a more urbanised environment, 3-monthly surveys were undertaken with surface waters, beach sediments, and M. gallloprovincialis mussels in Wellington Harbour, New Zealand, using samples from three sites for beach and mussel surveys, and two sites for the surface water tows. Weekly variation was also measured for beach sediments and mussel tissues. Again, no consistency was observed in temporal or spatial variation for any environmental or biological indicator, however the average pollutant loads were on par with reported results in other literature, particularly for M. galloprovincialis tissues. Temporally, the peak microplastic load in the tissues of the mussel, M. galloprovincialis, appeared to correlate with the peak load found within the surface waters of the harbour, indicating a possible relationship between plastic pollution in the environment and that which is found within organisms. Finally, the spatial variation observed within beach sediments was far larger than that seen throughout the mussel tissues, supporting the idea that beach sediments are microplastic sinks, but also susceptible to a range of environmental drivers including wind strength, wind direction, and sediment erosion.  Throughout the Southern Ocean and within Wellington Harbour, particle characteristics were similar, in that microfibres were the prevailing synthetic morphotype – accounting for upwards of 90% of all particles found. These results are similar to reports from other current literature, but not associated with public knowledge that is currently in the media and represented in the legislation. The results of this thesis illustrate the importance of monitoring and managing the occurrence and effect of microplastics on both fine- and broad-scales of temporal and spatial variation and helps address the knowledge gap surrounding microplastics in the Southern Hemisphere.</p>

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